Superheater



Sept. 24, 1957 Filed Dec. 20, 1954 G. A. REHM SUPERHEATER 5 Sheets-Sheetl INVENTOR. GUSTAV A. REHM PARKER 8. CARTER ATTORNEY Sept. 24, 1957 G.A. REHM 2,807,243

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INVENTOR. GU$TAV A. REHM PARKER CARTER ATTORNEYS United States PatentOSUPERHEATER Gustav A. Rehm, Springfield, Ill., assignor to SpringfieldBoiler Company, Springfield, Ill., a corporation of I This inventionresides in the field of steam boilers or the like and is an improvedtype of boiler unit and superheater structure adapted to increase thesteaming efficiency of the unit.

A primary object of my invention is a superheater for a package boilerso that the hottest steam will be in direct contact with the hottestgases.

Another object of my invention is a superheater with staggered tubes toget better gas flow between them.

Another object of my invention is a superheater arrangement in the formof a cage, closed on one side by a wall or baffle of circulation tubes.

Another object of my invention is a boiler structure of the above typehaving a superheater space in the form of a cage closed on one side withscreen tubes across its inlet side from the furnace space.

Another object of my invention is a boiler of the above type with a tubebafile wall at one end of the furnace space and at right angles to thegases so that the hot gases are required to turn approximately 90degrees to enter the superheater space'so that all of the superheatertubes will be exposed to approximately the same temperature gas. 7 4

Another object of my invention is a superheater of the above type whichis drainable,

Other objects will appear from time to time in the ensuing specificationanddrawings, in which:

Fig. l is a vertical section taken along line 1--1 of Fig. 3;

Fig. 2 is a sectional view taken along Fig. l;

Fig; 3 is a sectional View taken'along line 33 of Fig. 1;

11m 2-; of

' suitable outlet 46.

Fig. 4 is a sectional yiew taken along line 44'of Fig. 2; and V Fig. 5is a sectional view taken along line 55 of Fig. 2. g p v In Figs. 1, 2and 3,'the boiler unit has a housing 10 supported by any suitable base12 mounted on a suitable foundation 14. The housing is composed of twoside walls'16 and 18, a roof or top wall 20 and front and can be' madeout of any suitable insulation, such as mineral wool felt or the likedisposed in any suitable number of'laye'rs. The layers can be formed aspads or sheets of insulation disposed between steel plates, however thedetails are unimportant,

The boiler unit includes an upper drum 26 in the top A of theh'ousing'and a lower drum 28 disposed generally below it. Anintermediate longitudinal wall 30 divides rear walls 22 and 24respectively. The various Walls ,each other to allow free flow of theice space, after they have rounded the end 36 of-the intermediate wall,must flow through a tortuous path to a The furnace space is enclosed bythe usual water wall tubes 48 extending between the upper and lowerdrums. Natural circulation tubes 50 also" extend between the upper andlower drums and pass through the gas path.

The drums have suitable manholes 52 with suitable covers for inspectionand repair. The upper drum also has the usual connection 54 foratomizing steanya soot blower 55, a connection 56 for a soot blower, aconnection, 58 for safety valves, a connection 60 for a steam lance, anda vent 62, all of which are old, conventional and unimportant for thisinvention. A suitable water column '64 is provided, and the burner hasthe usual air inlet 66. The housing can be supplied with the usualobservation ports 68.

A superheater space 70 is located at the point ofcommunicationbetweenthe furnace space and the gas path. As. shown inFigure 2 this superheater space occupies the initial part of the 90degree turn 71 of gas path and projects into the fiurnace space.Roughly, the'superheater space is defined on two-sides by the walls ofthe housing, on the third side by a wall of baflle tubes 72, and on thefourth side by a row vof screen tubes 74. v 7 The battle tubes 72 liegenerallyin the same lateral plane and are interconnected between theupper and lower drums. The tubes generally rise from the lower drum,project laterally into the furnace space to form a wall or baffle andthen return to the gas path to the upper drum. The outermost tube 76extends approximately one-third to one-half of the distance across thefurnace space, while the innermost tube 78 is generally aligned with thewater wall tubes 48 along the intermediate longitudinal wall 30, asshown in Fig. 2. Considering these tubes indetail and taking theoutermost tube 76 as an example, in Fig. 5, it is provided with adiagonal portion 80 extending from the lower drum into the furnacespace. A vertical portion 82 rises through the furnace space and adiagonal portion 84 extends back and connects to the upper drum. Each ofthe bafile iTUlbES conforms generally to this same pattern, however theinside tubes have a slightly dilferent shape. For example, consideringtheinnermost tube 78, a vertical portion 86 extends upwardly from thelower drum, which turns into a diagonal portion 88 connecting to avertical piece 90 that is substantially shorter than the verticalportion 82 of the outermost tube, This vertical piece turns into adiagonal piece 92 extending back into the gas path to a vertical section94 which rises to the upper drum. It should be noted that the outermosttube 76 has the longest vertical section, and these vertical sectionsgradually diminish from one tube to the next, moving inwardly, until theinnermost tube 78 has the shortest vertical piece. 7 7 I Allof thebaffle tubes are directly next to each other, and although a slightspacing can be allowed, I prefer to have them directly next'to eachother. Thus an efifective wall of baffle tubes projects into thecombustion space and forces'the hot gases in a turning movement aroundthe baffle 72 and then into the superheater space. The wall of bafiletubes forces the gases to be flowing in generally a lateral directionwhen they enter the 'superheater The entrance to the superheater spaceis provided with the screen tubes 74 which, in shape or configuration,are generally similar to the outermost tube 76 in the baille .tubes. The.screen tubes are spaced substantially from gases into the superheaterspace.

. After the gases flow through the superheater space'and over thesuperheater elements, to be described more fully it also extendspartially into the furnace space.

3 hereinbelow, they flow through an opening 98 formed in the bafile wallas shown in Fig. 5. The bafiie tube 100 adjacent the inner edge of thebaffle tube wall projects upwardly in Fig. 5 but turns toward the wall18 and runs along it' to the top of .the housing where it enters theupper drum, as at 102, so that the opening 98 through the bafile tubesis not blocked.

A superheater, indicated in the superheater space and includes an inletheader 106 positioned in an opening 108 in the side walls'next to anoutlet header 110. Both the inlet and outlet headers are accessiblethrough the back wall for service, repair and the like. The inlet headeris connected to the upper drum by oneor more suitable tubes 112 runningalong the side wall. A plurality of tubes 114 extend from the inletheader into the superheater space, and after passing through a tortuousconfiguration, return to the outlet header. The tubes are disposed ingenerally parallel planes as shown in Figs. 1 and 2, and each includesan outlet portion 116 extending from theinlet header to a zig-zagsection 118 which rises to the top of the superheater space. Thiszig-zag portion merges into a comedown portion 120 which drops along theouter edge of the zigzag portion and, by a return portion 122, connectsto the outlet header 110.

Thus, each superheater tube 114 has a block or rectangular overallappearance. However, the steam passing through the tubes is forced totravel through a maximum distance due to the zig-zag formation 118. Thecomedown portions along the outside approach but are spaced from tubesand are staggered with relation to each other, as shown in Figure 2, toallow for a free flow of gases between the tube elements. All of thetubes lie in generally parallel planes and project laterally across thesuperheater space toward the screen tubes from the manifolds in the sidewalls 18. The inlet and outlet manifolds terminate at 124 in Fig. 2.

A baffie-type plate 126 extends the baflle tubes 72 and only partiallydirects or impedes the flow of the gases.

The use, operation and function of my invention are as follows:

I have shown and described what I consider a package unit boiler,however, of course, the inventive principle can be included in othertypes even though it is especially well suited to this type or style ofunit.

The unit fundamentally includes any source of heat with a water walledfurnace or combustion space to generate high temperature gases whichflow from the combustion space to a gas path where the heat from thegases is removed by a network of circulation tubes extending between theupper and lower drum structures. The gases flow out through any suitableoutlet. Between the combustion space and the gas path a superheaterspace is located. In this type of unit the combustion space and gas pathare disposed generally parallel and directly adjacent each other so thatthe gases must make a 180 degree turn from the furnace space to comeback through the gas path to the outlet. It is at this point that Ilocate the superheater space. Basically the initial part of the gas pathis appropriated for the superheater space, and It is very desirable tohave the maximum heat-transfer take place between the hot gases flowingfrom the furnace space and the superheater tubes. To do this I havearranged the superheater space and the superheater elements in a verydesirable manner.

To acquire the maximum heat transfer, it is desirable that the hot gasesflow with a turning or rotating motion over the superheater elements.The gases must therefore -be made to turn 90 degrees, or approximately90 degrees, before they contact the superheater elements. To make thegases turn 90 degrees before entering the superheater space, I provide awall of bafile tubes extend ing laterally from the intermediate wallwhich, in effect, masks the superheater elementsand forces the gases togenerally at 104, is positioned turn also in the superheater space aftermaking the degree turn. The entrance to the superheater space isprovided with a collection of spaced screen tubes to strain the gasflow.

After flowing over the superheater tubes the gases are allowed to enterthe tortuous gas path through a gap in the wall of baffle tubes. Itshould be noted from the configuration of the baffle tubes in Fig. 5that the centralized gap 98 will cause a converging action of the gasesand will tend to center them.

The superheater bundle positioned in the superheater space is composedof inlet and outlet headers which are each positioned in an opening inthe side wall so that they can be easily serviced, withdrawn, orreplaced. A collection or manifold of tubes extend from these headers upinto the superheater space and each is bent into a zigzag or tortuousconfiguration to provide the maximum length of tube in the space and isarranged so that each tube is self draining. The tubes are generallyparallel and the forward edges confronting the incoming hot gases arestaggered so that the gases can flow between them without interference.

It should be noted that the hottest steam in the superheater will bedirectly next to the hottest gases, namely the incoming gases, and thisis very desirable.

In effect, the superheater is positioned in a cage closed on one sidewith screen tubes across its open side.

It is important that all of the superheater tubes be subjected to thesame temperature gases. Due to the 90 degree turn of the'gases caused bythe wall of baffle tubes, the gases entering the superheater spacethrough the screen tubes will have approximately the same temperature.

While I have shown and described a preferred form of my invention, itshould be understood that numerous modifications, changes, substitutionsand alterations can be made without departing from the fundamentaltheme. For example, the details of the upper drum are old, as shown inFigure 3, however, any suitable upper drum can be used which provides abaffle and steam purifier ahead of the connecting tubes between theupper drum and the inlet header for the superheater. The tubes in thebaffle wall 72 can touch each other or be slightly spaced as in Figures3, 4, and 5 so long as they function as set forth herein above. Thedetails of the drums have been eliminated from Figures 1 and 4 forclarity. Likewise, the soot blowers, safety valves, vents, observationports, and all the other standard items, are not important but have onlybeen shown to round out the disclosure. While I have shown aconventional burner, it should be understood that gaseous, liquid orsolid fuels could be used. I therefore wish that my disclosure be takenas exemplary or diagrammatic and not in a limiting sense except as by'the appended claims.

the rear wall generally aligned with the gas path and constructed toreceive the flow of hot gases from the furnace space, superheaterstructure in the superheater space, including generally parallel inletand outlet headers disposed longitudinally in the side wall so as to beremovable and generally adjacent each other, one above the other, theupper header being an inlet header and the lower header being an outletheader, a plurality of superheater tubes connected between the headersin generally parallel planes at right angles to the headers, the path ofeach tube being tortuous leading away from the inlet header andincludinga zig-zag section with laterally horizontal, rectilinearlengths and integral, connecting bends providing an over-all, generallyrectangular outline, the sides of the outline away from the headersbeing alternately staggered in relation to each other, the tubes beingconstructed to receive hot gases from the furnace space in a directiongenerally parallel to the plane of the tubes, the return line from theoutline to the outlet header having a straight, generally verticalsection remote from the headers in the path of the incoming gases fromthe furnace space, and a lateral wall of circulation tubes in the lineof flow of the hot gases from the furnace space ahead of the superheaterstructure, the superheater tubes and wall of circulation tubes beinggenerally perpendicular to the furnace space, the entrance to thesuperheater space having a longitudinal line of screen tubes across itgenerally aligned longitudinally with the end of the wall of circulationtubes.

2. The structure of claim 1 further characterized in that thesuperheater tubes are generally parallel and are staggered in theirlateral extent from the headers.

3. The structure of claim 1 in which the superheater tubes arealternately staggered.

4. In a boiler structure, a housing having front, rear and side wallsdefining a furnace space and gas path generally parallel to each other,a longitudinal wall between them which terminates a substantial distancefrom the rear Wall of the housing, an opening in the side wall, means inthe housing defining a superheater space at the end of the longitudinalwall occupying the entire corner at the rear wall and side wall thatdefines the gas path, a superheater structure in the superheater spaceincludin an upper inlet header and a lower outlet header disposed insaid opening in the side wall so as to be removable and generallyparallel and adjacent each other, one above the other, a plurality ofsuperheater tubes connected generally at right angles between theheaders, the path of each tube leading away from the inlet header beingtortuous and longitudinally aligned with the gas path but presenting agenerally over-all rectangular outline, the return line to the outletheader having a straight, somewhat vertical section remote from theheaders in the path of the incoming hot gases, the straight sections ofeach tube being staggered in relation to the straight sections ofadjacent tubes, and means for turning the hot gas approximately 90 asthey enter the superheater space.

5. The structure of claim 4 further characterized in that thesuperheater space occupies only the corner at the rear wall and sidewall that defines the gas path, and further characterized in that saidmeans for turning the hot gases approximately as they enter thesuperheater space includes a lateral wall of circulation tubes generallyin the line of flow of hot gases from the furnace space ahead of thesuperheater structure.

6. In a boiler structure, a housing having front, rear and side wallsdefining a furnace space and gas path generally parallel with eachother, a longitudinal wall be tween them which terminates a substantialdistance from the rear wall of the housing, an opening in the side wall,means in the housing defining a superheater space at the end of thelongitudinal Wall aligned at least with the gas path, a superheaterstructure in the superheater space including at least an outlet headerdisposed in said opening in the side wall so as to be removable, aplurality of superheater tubes connected to the header in generallyparallel planes and at right angles to the header, the path of each tubebeing tortuous and including a zig-zag section with laterallyhorizontal, rectilinear lengths and integral, connecting bends providingan over-all, generally rectangular outline, the rectilinear lengths andintegral, connecting bends being aligned generally with the gas path toprovide a minimum resistance to the flow of hot gases through thesuperheater space into the gas path, a lateral wall of circulation tubesgenerally in the line of flow of hot gases from the furnace space aheadof the superheater structure, the superheater tubes and Wall ofcirculation tubes being generally perpendicular to the furnace space,and a longitudinal line of screen tubes across the entrance to thesuperheater space.

References Cited in the file of this patent UNITED STATES PATENTS1,999,983 Schmidt Apr. 30, 1935 1,999,984 Bailey et al. Apr. 30, 19352,561,839 Behr July 24, 1951 FOREIGN PATENTS 245,325 Great Britain Ian.7, 192.6

616,011 Great Britain J an. 14, 1949

